I just found this does not work for me. I'm using the new Windows 7. When I checked that registry key (before trying to delete it), I found that it did not have all the server/host IPs that should be there. Afterwards, when I did a search for "VNC", I finally found a ..\Software\ORL\VNCviewer\MRU registry key in the HKEY_USERS tree, under a really long numeric key, that had all the current IPs in the list. Modifying that key yielded good results.

It should be, but it wasn't for me. *Hmmm* It is highly possible that I installed the viewer under an administrator account (and of course, used the viewer only in a user account), and the viewer has only been storing the IP numbers in the administrator account's copy of the MRU key.

Update: Nope, your right; I essentially kept running regedit as an administrator. If I run regedit regularly, I can view the correct MRU key in HKEY_CURRENT_USER. A pity; as a user, I can only "merge" a reg file into the registry via the command line, "regedit /s".